Cutting insert



June 8, 1965 F. M. FRANKo 7 3,187,406

CUTTING INSERT Original Filed June 14, 1963 22 F 6 Z? IG. IG. F 3 2/fNl/ENTOF? fkEDR/CK M. FRANKO CIAMQ H/s A TTORNEY United States PatentC) 3,187,406 CUTTING INSERT Frederick M. Franko, Johnstown, N.Y.,assignor to General Electric Company, a corporation of New YorkContinuation of application Ser. No. 287,891, June 14, 1963. Thisapplication Dec. 16, 1964, Ser. No; 421,149

. 3 Claims. (CI. 29-95) This is a continuation of application Serial No.287,891 filed June 14, 1963, now abandoned.

This invention relates to a disposable cutting insert of the type usedin a cutting tool for the machining of metals and, more specifically, toa disposable cutting insert which contains an integral chip controllinggroove therein and to a cutting tool provided with such insert.

In the machining of metal with cutting tools, a ribbon of metal isremoved during the machining operation. This ribbon of metal isredirected as it strikes the cutting tool, the workpiece, portions ofthe tool post in which the cutting tool is held or other elements inproximity to the cutting tool and is broken into short, controllablelengths or chips. This ribbon of metal must be controlled and brokeninto chips to avoid interference with the machining operation, to avoidsafetyhazards to the operator and for ease of handling.

Most cutting tools in use today of the type in which an insert ismechanicallyheld in a cutting toolholder possess an element whichfunctions to direct the ribbon of removed metal or chips in acontrolleddirection. Such chip controlling elements, frequently referred tosomewhat inaccurately as chip breakers, are usually in some wayassociated with the clamp which holds the insert in place. The clampeither serves to hold a chip controlling element in place or,alternatively, a surface of the clamp itself performs the chipcontrolling function.

There has recently been developed a cutting tool in which the cuttinginsert is releasably held in the cutting tool shank by an eccentric pin,thus eliminating the necessi'ty for any. mechanical clamping elements.An important advantage of such cutting tools is their simplicity indesign and reduced number of components, advantages which would,in'largemeasur -be defeated by the addition of separate clamping or chipcontrolling elements.

It is, accordingly, aprimary object of this invention to provide adisposable insert for a cutting tool which insert functions to controlchip direction etficiently and effectively.

It is an additional object of this invention to provide a cutting toolof great simplicity in design and function in which the cutting insertis utilized to control chip direction and which neither requires norpossesses separate chip controlling elements.

These and other objects will become apparent from the discussion of theinvention which follows in conjunction with the accompanying drawings inwhich:

FIGURE 1 is a perspective view of one embodiment of a cutting tool ofthe invention;

FIGURE 2 is a view partly in cross-section and partly in elevation ofthe cutting tool head taken along the line 22 of FIGURE 1;

FIGURE 3 is an enlarged elevational view, partly broken away, of thecutting insert shown in the cutting tool of FIGURES 1 and 2;

FIGURE 4 is a still further enlarged fragmentary view of the cuttinginsert of FIGURES drawn to scale and showing in detail the configurationof a chip controlling groove of the invention.

FIGURES 5, 6 and 7 are schematic views showing the manner in which achip strikes the surface of a cutting insert of the invention.

FIGURES 8, 9, 10 and 11 show different embodiments of cutting insertsfalling within the scope of the invention;

will function effectively to control chip direction while stillretainingthe indexible, invertible features of a disposable insert. Thecritical design features of the cutting insert, described more fullyhereinafter, include the use of a groove which is continuous and whichhas a dual radiusthe back radius is greater than the forward radius. Inaddition, a circumferential land exists between the groove and thecutting edge which is offset from the remaining surface of the face ofthe insert.

Referring to the drawings, FIGURES 1 and 2 show one embodiment of acutting tool of the invention. The cutting tool comprises a shank 1 of aheat-treated, tough steel having an open recess 2 at one end thereof.The recess has two supporting surfaces, base 3 and a shoulder or rearsupporting surface 4, for supporting a cutting insert 5 and a seat 6 forthe cutting insert. The insert 5 and seat 6 are held in the open recessof the shank by cam pin 7 of high alloy, tough steel having an eccentricextension 8. The cam pin 7 is anchored in the shank 1 by spring clamp 9which locks in a counterbore 10 in the inner diameter of the hole 11 ofthe shank. The eccentric ex tension 8 of cam pin 7 fits into a centralhole 12 in insert 5. When the cam pin is rotated in a first direction,the eccentric extension forces insert 5 against rear shoulder 4 of theshank and the insert is locked in place by frictional forces alonebetween the cam pin, insert and rear shoulder of the shank. By rotatingthe cam pin in the opposite direction, the insert is loosened and may befreely rotated and removed for indexing and inversion of the cuttinginsert. The cam pin is conveniently rotated by the insertion of an Allenwrench in a recess 13 in pin 7. Annular flange or collar 14 incombination with spring clip 9 retains the cutting seat 6 in placeduring indexing and removal of the seat. The cam pin and seat are easilyremoved from the shank by a light tap with a pointed tool against thebottom of the pin.

An important feature of the present invention resides in the fact thatit is useful in cut-ting inserts of the socalled disposable type; thatis, inserts possessing a plurality of useful cuttings edges. In the caseof the square insert shown in FIGURE 1, there are eight availablecutting edges. When one of the edges has become dull or otherwise notfurther usa-b1e,-the insert is indexed by loosening the cam pinand'rotating the insert When all four upper cutting edges have beenused, the insert is inverted and four additional cutting edges areavailable. For full utilization of such disposable inserts, the cuttingtool must provide chip control when each of the cut-tingedges is incutting position. The present invention provides a cutting insert havinga chip controlling groove of such configuration and dimensions thateffective chip control is provided when any of the cutting edges of theinsert is in cutting position. The invention therefore makes possible acutting tool for disposable inserts possessing all of the func tions ofprior cutting tools but having significantly fewer components and ofmuch greater simplicity in design.

FIGURES 3 and 4 illustrate in greater detail the configuration anddesign of the cutting insert of the invention. As there shown,the-cutting insert has parallel faces ill-5 and .16, peripheral or edgesurfaces 17 and a central hole or aperture 12 to receive eccentricextension 8 .of pin 7. Peripheral surfaces :17 and central aperture 12are parallel to each other and both are perpendicular to parallelsurfaces 15 and 16. The peripheral surfaces and the parallel faces meetto form a plurality of cutting edges 18 (see FIGURE 1), each of which isof the same length. The cutting insert possesses a continuous, curved,chip controlling groove -19 on both of its parallel faces, The

groove possesses a constant cross-sectional shape. It should, of course,be understood that at the corners of a square or other polygonal-shapedinsert, the cross-sectional shape may deviate somewhat where the groovechanges direction. Groove 19 is spaced equidistant from the cuttingedges 18 so that a circumferential land 20 is formed on each face of thecutting insert between groove 19 and cutting edge 18. As can be seenfrom the drawings, the surface of land 20 is offset or lower than theremaining surface of the parallel face. Thus, as most clearly shown inFIGURES 3 and 4, the axial depth of the land of the cut-ting insertadjacent the cutting edge is less than the axial depth of the centralland of the cutting insert. (The axial direction as used herein is adirection parallel to aperture 12 in the insert.) The presence ofcircumferential land 20 is a necessary feature of the invention. Itsomission has been found to result in insuificient strength of cuttingedges 18. Moreover, if the land is not offset as described, the insertwill tend to fracture during cutting operations because of contactbetween the land and the supporting surface of the recess of the shankor the supporting surface of the seat on which the cutting insert rests,

Specific dimensions of the various configurations of the insert will toa certain extent be dependent on the feed, speed and depth of cut, thenature of the material being machined and on other machining operationvariables. However, certain of such dimensions have been found to have afixed range of values which are useful for a wide variety of cuttingconditions and these preferred dimensions will therefore be set forth.

As shown in FIGURE 4, the depth D of the groove as measured from thesurface of the circumferential land to a plane tangent to the bottom ofthe groove is preferably from .001 to .010 inch and even more preferablyfrom .003 to .006. The groove width W is a function of the width of thecircumferential land but preferred values for these dimensions are .035to 0.10 inch groove width and .003 to .040 inch land width.

The front radius R of the groove, the radius nearest the cutting edge,is preferably from .040 to .050 inch. The dimension of the inner or rearradius R the radius furthest removed from the cutting edge, is afunction of the dimensions of the groove and of the front radius but isgreater than radius R as illustrated in FIGURE 4. The use of a dualradius (where R is greater than R has been found to be superior to asingle radius in its chip controlling function during machiningoperations. Reference herein to a front and rear radius is intended torefer to the predominant slope of the groove. It may be desirable tomodify slightly the slopes of the beginning and terminal portions of thegroove and thus in effect to have four radii. In any event, the inner orrear por tion of the groove should have a shallower slope than theforward portion, or stated otherwise, the groove should have at leasttwo radii in which rear radius R is greater than front radius R Wherebrittle materials, such as cast iron, are machined, chip control israrely a problem. Such materials produce short, trouble-free chips whenmachined even at high rates of feed. However, for the machining of steeland other ductile materials, chip control is mandatory. About 80 percentof all machining operations fall in the latter category in which chipcontrol is necessary. The manner in which chips are redirected orcontrolled in accordance with the invention is illustrated in FIGURES 5,6 and 7 at three different feed rates. Such feed rates ordinarilydetermine the manner in which the chip contacts the surface of thecutting insert. Feed rate, a measure of the speed of metal removal, isordinarily classified as either light, medium or heavy. At light feedsof approximately .006 to 0.016 inch per revolution, the removed ribhonof material or chip 22 contacts both the near and far radii of the chipcontrolling groove .19 as shown in FIGURE 5. The chip is then redirectedand broken into chips upon contact with workpiece 21 or other portionsof the tool post or cutting tool. At medium feeds of approximately .017to .032 inch per revolution, the removed metal 22 contacts the farradius and/ or back edge of groove d9 as shown in FIGURE 6, and isredirected and broken into chips as set forth above. At heavier feeds inexcess of about .032 inch per revolution, the removed material strikesthe upper parallel face of the insert beyond the groove as shown inFIGURE 7, and is thereafter broken into chips.

Accordingly, the chip controlling groove of the present inventionfunctions to control the flow and direction of chips so that the chipsare effectively broken in a fully satisfactory manner. Moreover, theresult is accomplished without the presence of overhead clampingelements which tend to obstruct and interfere with chip flow as thechips sweep across the face of the cutting insert. Moreover, such clampsare frequently damaged or fractured at the heavier feed rates.

Chip controlling grooves of the invention may be utilized in cuttinginserts of other than the configuration illustrated in FIGURES 1 through4. Other illustrative cutting insert shapes are illustrated in FIGURES8, 9, 10 and 11. FIGURE 8 shows a triangular insert 26 containing chipcontrolling groove 27. FIGURE 9 shows cutting insert 28 in the shape ofa regular octagon containing chip controlling groove 29. FIGURE 10 showsa circular insert 30 containing a chip cont-rolling groove 31. FIGURE 11shows a rectangular insert 32 containing chip controlling groove 33. Inall instances, the dimensions and configuration of the chip controllinggroove and the land conform to those set forth for the groove of FIGURES1 through 4.

The invention thus provides for successful control of chip formation ina cutting tool of very great simplicity. A single insert has been foundto be capable of chip control over a wide range of materials, feeds anddepths of cut thus resulting in greater versatility of use of a singlecutting tool-insert combination. Moreover, the complete symmetry of theinsert configuration enables one style of insert to serve for bothrightand left-hand cutting and to control chips with equal effectivenessin both types of cutting.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A disposable cutting insert having parallel faces and a peripheralsurface along the axis thereof,

said parallel faces and peripheral surface meeting to form a pluralityof cutting edges,

each of said parallel faces having a continuous, curved,

chip-controlling groove therein of uniform, crosssectionalconfiguration,

said groove being spaced equidistant from said cutting edges to form acentral island and a circumferential land on said parallel faces,

the axial depth of said land being less than the axial depth of saidisland and the portion of .the groove adjacent the land having a firstradius, the remainding portion of the groove having a second radiusgreater than the first radius. 2. An indexible and invertible cuttinginsert having parallel faces, a peripheral surface normal thereto andalong the axis thereof and an axial hole therein,

said parallel faces and peripheral surface meeting to form a pluralityof cutting edges of equal length,

each of said parallel faces having a continuous, curved,

chip controlling groove therein of uniform, crosssectionalconfiguration,

said groove being spaced equidistant from said cutting edges to form acentral island and a circumferential land on said parallel faces,

the axial depth of said land being less than the axial depth of saidisland and the portion of the groove adjacent the land having a firstradius, the remaining portion of the groove having a second radiusgreater than the first radius. said groove being spaced equidistant fromsaid cutting 3. A disposable cutting insert having parallel faces edgesto form a central island and a circumferential and a peripheral surfacealong the axis thereof, land on said parallel faces,

said parallel faces and peripheral surface meeting to the axial depth ofsaid land being less than the axial form a plurality of cutting edges,5' depth of said island. each of said parallel faces having acontinuous, curved, v No references cited.

chip-controlhng groove therein of uniform, crossti l gonfiguration, 7ANDREW R. JUHASZ, Primary Exammer.

1. A DISPOSABLE CUTTING INSERT HAVING PARALLEL FACES AND A PERIPHERALSURFACE ALONG THE AXIS THEREOF, SAID PARALLEL FACES AND PERIPHERALSURFACE MEETING TO FORM A PLURALITY OF CUTTING EDGES, EACH OF SAIDPARALLEL FACES HAVING A CONTINUOUS, CURVED, CHIP-CONTROLLING GROOVETHEREIN OF UNIFORM, CROSSSECTIONAL CONFIGURATION. SAID GROOVE BEINGSPACED EQUIDISTANT FROM SAID CUTTING EDGES TO FORM A CENTRAL ISLAND ANDA CIRCUMFERENTIAL LAND ON SAID PARALLEL FACES, THE AXIAL DEPTH OF SAIDLAND BEING LESS THAN THE AXIAL DEPTH OF SAID ISLAND AND THE PORTION OFTHE GROOVE ADJACENT THE LAND HAVING A FIRST RADIUS, THE REMAINDINGPORTION OF THE GROOVE HAVING A SECOND RADIUS GREATER THAN THE FIRSTRADIUS.